JPH0323963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal (video signal format such as PCM recording of an audio signal) recorded on a magnetic tape by a rotating head type magnetic recording/reproducing device (hereinafter referred to as VTR). (including cases where it has been converted to
In particular, it allows reproduction at a faster speed than the tape speed at which it was recorded.

Conventionally, there are two types of videotape duplication methods: The first is the so-called VTR-VTR recording method, in which a large number of VTRs are lined up and the reproduction signal of one parent VTR is recorded on each VTR.
The second method is a duplication method that does not use head recording, by bringing the master tape on which the original signal has been recorded and the unrecorded slave tape into contact with each other's magnetic surfaces, and applying a magnetic field or heat to transfer the signals from the master tape to the slave tape. It is a contact transfer method.

Recently, VTRs have become extremely popular, and mass duplication is required to supply a large amount of video software (recorded tapes).
In the first method, it takes real time to copy, which increases the cost, whereas in the second method, it does not require real time to copy, and therefore video software can be created at low cost, so it will become more expensive in the future. It is thought that it will become mainstream.

However, the popularity of VTRs in homes has increased significantly for portable types that come with video cameras, and these VTRs are often used to record and enjoy video by oneself. Then, a request arises to make a copy of the recorded tape and send it to a friend or family.
In such cases, it would be very convenient if there was a device that could easily reproduce magnetic tapes at home. In this case, since there is no mass duplication, the first method is used.
The VTR-VTR recording method is advantageous in terms of equipment scale. For VTR-VTR duplication, prepare two VTRs,
This can be done by loading a recorded tape into the first VTR and putting it into playback mode, and using the playback signal as the input signal for the second VTR, by loading an unrecorded tape into the second VTR and putting it into recording mode. . In this case, the time required for duplication is the same real time as the recording time of the recorded tape, making the duplication work cumbersome. Furthermore, in order to speed up VTR-VTR duplication, devices have been proposed in which the number of rotating heads is increased and the diameters of the rotating head cylinders are varied, but it is difficult to mass-produce VTR-to-VTR duplication devices for home use.
This becomes somewhat complicated, and the frequency of the video signal increases, making it difficult to handle.

The present invention addresses the above-mentioned needs and solves the problems of the prior art, and provides a device that can perform videotape duplication using a relatively simple device in a shorter time than the recording time. .

Hereinafter, the present invention will be explained with reference to the drawings. Figure 1 is a diagram showing the relative relationship between the rotating head and magnetic tape of an azimuth recording VTR, which is currently popular for home use, and Figure 2 shows the relative relationship between the rotary head and the magnetic tape.
FIG. 2 is a diagram schematically showing a tape pattern recorded by a VTR. on the outer circumference of rotating cylinder 1
Rotary heads 2 and 3 are mounted so as to maintain a 180° positional relationship, and rotary cylinder 1 rotates in the direction of arrow A at 30 revolutions per second. Rotating heads 2 and 3
have different gap inclination angles, and are represented by R and L, for example. A video signal recorded with the R rotary head cannot basically be reproduced with the L rotary head, and can only be reproduced with the R rotary head. will be played. The magnetic tape 4 is wound around approximately half the circumference of the rotating cylinder, and is arranged at a predetermined angle of inclination with respect to the rotating cylinder as shown by arrow B.
It is configured to run at a constant speed in the direction. Therefore, for example, the track pattern recorded by the rotary head 3 becomes a track inclined with respect to the magnetic tape 4, as shown at 5. Figure 2
R ₁ , L ₁ , R ₂ , L ₂ , R ₃ , L ₃ designate the tracks thus recorded by the rotating heads 2 and 3, and R ₁ , R ₂ , R ₃ are the azimuth angles. is the track recorded by the rotating head 2 of R,
Tracks L ₁ , L ₂ and L ₃ are those whose azimuth angle is recorded by the rotating head 3. Video signals are recorded on these tracks, and are usually a signal obtained by superimposing a signal obtained by frequency modulating a luminance signal and a signal obtained by reducing and converting a carrier color signal. magnetic tape 4
In addition to this video signal, there are a control track 6 and an audio track 7, and the control signal and audio signal are recorded by separate fixed heads.

FIG. 2 is a view of the magnetic tape 4 viewed from the magnetic surface, with arrow B indicating the running direction of the magnetic tape and arrow A indicating the running direction of the rotary head.

Now, let us consider the case where a magnetic tape recorded as shown in FIG. 2 is to be reproduced. The tape speed T _T and the rotating head speed T _H are the same as during recording, and the positional relationship between the rotating head and the magnetic tape is kept constant by a servo loop using the control signal recorded on the control track 6 and the rotating cylinder position signal. It is well known that if the rotary heads 2 and 3 are controlled in the correct manner, they will correctly scan the recorded tracks R ₁ , L ₁ , R ₂ , L ₂ , . . . and the video signal will be correctly reproduced. be. It is possible to duplicate the video signal that has been correctly played back in this way by recording it on another VTR, but
In this case, it takes the same amount of time to reproduce the parent tape as it does to record it, resulting in a long duplication time.

The present invention makes it possible to shorten the replication time, and in principle, it can be shortened to any time.

In order to shorten the duplication time, the reproduction time of the parent tape can be made shorter than the recording time, and the data can be recorded on the child tape at the same time. In short, it is sufficient if the playback time can be shortened without losing all the video information of the parent tape. In order to shorten playback time, it is necessary to make the playback tape speed faster than during recording. Consider the case where a tape having the recording pattern shown in FIG. 2 is played back at, for example, double speed. Since the control signal on control track 6 and the audio signal on audio track 7 are reproduced by a fixed head, = υ/λ λ: Recording wavelength υ: Tape speed: From the relationship of frequency, the frequency only doubles. If the data is recorded on a child tape running at twice the speed, the same signal as that on the parent tape will be recorded on the child tape and duplication will be performed.

However, the video signal depends on the speed of the rotating head.
Since V _H is the same as during recording and the tape speed V _T is doubled, the trajectory of the rotary head straddles the two recording tracks as shown at 8, 9, and 10 surrounded by the broken line in Figure 2. It becomes a vine. Now, if the scanning locus 8 is assumed to have an azimuth angle of R, the scanning locus 9 is alternately switched to L and 10 to R. The rotary head output when the playback tape is run at twice the speed is shown in FIGS. 3a and 3b in comparison with the head switch signal used to switch the rotary head. A in the figure is a head switching signal, which is obtained from a rotational position detector attached to the rotating cylinder, and is normally a 30Hz rectangular wave. For example, when this signal is "H", the rotating head 2 is magnetically tape 4
The rotary head 3 scans the magnetic tape 4 during the "L" period. Therefore, 1/60 at the left end in the diagram
The rotary head 2 scans the magnetic tape 4 for a second, and since the scanning locus 8 is the same, the rotary head 2 picks up only the R azimuth signal, resulting in a downward-sloping head output signal as shown in Figure 3b, which is record track
This is the signal of _R1 . Similarly, for the next 1/60 second, the rotating head 3 with the azimuth angle L scans the scanning locus 9, so the head output signal has an upward slope to the right, which is the signal of track _L2 . Similarly, R ₃ , L ₄ ,
This becomes the playback output of R ₅ , L ₆ , .... This reproduction signal is generated from recording tracks L ₁ , R ₂ , L ₃ , R ₄ , L ₅ , R ₆ , . . . of the video signals recorded on the magnetic tape 4.
This indicates that the signal of ... cannot be reproduced. Furthermore, the signal of the reproduced track is not always 100%, and there is an attenuation portion during each field period (1/60 second), resulting in a poor signal-to-noise ratio. If such a reproduction signal is recorded on a sub-tape, there will be fields in which the video signal is missing, and there will also be attenuated portions within the fields, making it impossible to reproduce the original video signal at all.

As is clear from the above description, the key to shortening the duplication time lies in how to prevent video signal dropouts and signal attenuation when playing back tape at an increased tape speed.

In order to make this possible, the present invention increases the playback speed of the parent tape, increases the number of rotating heads provided on the rotating cylinder, and also adopts a structure that gives an appropriate inclination to the rotational axis of the rotating cylinder.
To reproduce a parent tape by configuring a desired recorded track to be correctly scanned even if the tape speed during reproduction increases. Then, recording on the secondary tape is performed by running the secondary tape at the same tape speed as the reproduction system, and recording the signal reproduced as described above multiple times through a rotating cylinder whose rotational axis has the same inclination as that for recording. This is done using the head.

Next, the principle and embodiments of the videotape duplicating apparatus of the present invention will be explained with reference to the drawings.

FIG. 4 is a model diagram showing a group of rotating magnetic heads for realizing high-speed replication according to the present invention. The rotating cylinder includes six rotating heads P _R1 ,
Arrange P _R2 , P _R3 , P _L1 , P _L2 , and P _L3 . That is, three pairs of heads with different azimuth angles are arranged on a straight line (180°) at 60° intervals so that the azimuth angles L and R are alternately different along the circumference.

Figure 5 shows the tape track pattern of the parent tape.
L ₁ , R ₁ , L ₂ , R ₂ , . . . and the scanning loci (head center line) of each rotary head shown in FIG. 4 are indicated by broken lines. Since the tape speed V _T is three times the recording speed and the rotating head is at the same speed, for example, the rotating head is
P _L1 scans across three tracks, L ₁ , R ₁ , and L ₂ . In this state, only the signals of tracks _{L 1} and R ₁ having the same azimuth as PL1 are picked up, and no signal is reproduced when scanning the track of R ₁ . Therefore, the rotating head receives the desired track signal.
To pick up 100%, it is necessary to correct the slope of the scanning trajectory. In this case, in order to reproduce the _L1 track with P _L1 , the head should not be moved at the scan start point of P _L1 , but should be moved two track pitches to the left of the track at the end of the scan. To achieve this, as shown in FIG. 6, the inclination angle of the rotary cylinder with respect to the tape reference plane is shifted by a from the inclination angle θ at which the parent tape was recorded. Due to this difference in the angle of inclination of a, when the magnetic tape 4 runs at three times the speed in the direction of arrow B, each rotating head 11, 12
The recording head scans the tape pattern parallel to the recorded track, allowing complete tracking, and each rotating head receives the signal of the desired track.
100% can be picked up. In addition, 13 indicated by a solid line in FIG. 6 indicates a conventional cylinder, and 14 indicated by a dotted line indicates a cylinder according to the present invention. Also, 15
indicates the tape reference plane.

Figures 7a, b, and c show the head switch signals corresponding to each pair of rotating heads, P _L1 and
P _R1 is switched by head switch 1, P _R2 and P _L2 are switched by head switch 2, and P _L3 and P _R3 are switched by head switch 3, and each head switch signal has a phase difference of 60 degrees.

As mentioned above, after P _L1 reproduces 100% of the signal from track _L1 , the magnetic tape advances at three times the speed, so
P _R1 will come to the bottom of the _R2 track as shown in Figure 5. Here, since the rotating head has the above-mentioned inclination, the _R2 track is scanned as shown in FIG. 7g, and 100% reproduction output is obtained. The _L1 track is reproduced by scanning P _L1 , and the _R2 track is reproduced by scanning P _R1 , but there are _R1 and _L2 tracks between them. This is reproduced by P _R2 and P _L3 , and by placing them at 60° positions, they will be at the lower ends of the R ₁ and L ₂ tracks in Figure 5, and as shown in Figure 7 e and f. As shown, the signals of R ₁ and L ₂ tracks are
100% playable. Similarly, by P _L2 and P _R3 , L ₃ ,
Can reproduce 100% of _R3 track signals.

In this way, by tilting the rotation axes of the six heads provided on the rotary cylinder by two track pitches with respect to the diameter, images of all tracks on the recording tape can be obtained from the six rotary heads, although they overlap in time. Since the signal can be reproduced, if this signal is recorded on the child tape at three times the speed in the same process, it will be recorded in the same recording pattern as the parent tape. In this way, replication at three times the speed is possible.

As mentioned above, an odd multiple (n+1) of the tape speed during recording is selected, and (n+1) pairs of rotary heads (one pair refers to two heads with different azimuth angles located at 180 degrees) are provided. By tilting the rotation axis of the rotary head by an angle that provides perfect tracking, each head provided on the rotary cylinder can sequentially reproduce tracks with different azimuth angles. For recording, a rotary cylinder with the same configuration is used, and by recording the video signal while running the magnetic tape at the same speed as the reproduction speed, duplication at odd-numbered speeds can be realized.

According to this device, the cylinder diameter and rotational speed of the cylinder are the same as usual, so the relative speed between the magnetic tape and the rotating head does not change significantly, and the frequency of the reproduced video signal is almost the same as usual. Since the frequency is not particularly high, conventional circuits are sufficient for both the reproducing amplifier and the recording amplifier.
Furthermore, with an azimuth-type VTR, heads with different azimuth angles are placed at 180° positions on the rotating cylinder, so playback and recording at normal speed can be easily performed by returning the rotating cylinder to its original tilt angle. obtain. In other words, normal playback can be achieved by making the tape running speed the same as when recording the parent tape and extracting the output from the rotary heads that are positioned at 180 degrees.
Similarly, recording at normal speed is also possible.

Although the above embodiment described a method for reducing the replication time to 1/3, according to the present invention, by increasing the number of rotating heads, the replication time can be further reduced, and in principle is infinitely possible.

As described in detail above, according to the present invention, since a video tape can be copied from a parent tape to a child tape in a short time, an individual can easily copy a VTR tape without the need for a large-scale device. This can be expected to have the effect of further promoting the spread of VTRs. Furthermore, it can be effectively used not only for copying but also for personal editing work. In the above-described embodiment of the present invention, a duplication-only device having two lines of rotating cylinders was described, but the conventional
In addition to the VTR function, if the VTR is equipped with recording system and playback system functions according to the present invention, high-speed duplication is possible by combining two VTRs, so it can also be used as a kind of additional function. Furthermore, even if it is a reproduction-only device, normal playback and normal recording are also possible, which is a great advantage in terms of versatility.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relative relationship between the rotating head of a rotating head VTR and the magnetic tape, Figure 2 is a diagram showing the signal track on the magnetic tape recorded in an azimuth recording type VTR and the scanning trajectory of the rotating head, and Figure 3 is a diagram showing the relative relationship between the rotating head of a rotating head VTR and the magnetic tape. a,
Fig. 4 shows an example of the head arrangement of the rotating cylinder used in the present invention, and Fig. 5 shows the track pattern on the magnetic tape and the scanning of the rotating head. FIG. 6 is an explanatory diagram of the trajectory, FIG. 6 is an explanatory diagram of the inclination angle of the rotary cylinder used in the present invention, and FIG. 7 is a sequence diagram showing the head switch signal and each rotary head output in the embodiment of the present invention. 1...Rotating cylinder, 2, 3, P _R1 ~ P _R3 , P _L1
~P _L3 , 11, 12... Rotating head, 4... Magnetic tape.

Claims (1)

[Scope of Claims] 1. A tape running system comprising a first tape running system and a second tape running system;
The recorded tape is run in the tape running system, and the unrecorded tape is run in the second tape running system, and the tape running speed of the first and second tape running systems is set to the recording speed of the recorded tape. The rotating cylinders in the first and second tape running systems are provided with a plurality of rotating heads, and each of the rotating heads has an inclination of its axis of rotation at the time of recording the recorded tape. The rotary shaft has a structure in which the inclination of the rotary axis is different, and the playback output of each rotary head in the first tape running system is applied to each rotary head in the second tape running system, so that the signals of the recorded tape are transferred to the unrecorded tape. A videotape duplicating device characterized in that it is configured to record on. 2. The tape speed of the first and second tape running systems is an odd number multiple of the recording speed of the recorded tape, and the rotating head is provided with an odd number of pairs of heads with different azimuths. A videotape duplicating device according to scope 1. 3. The videotape according to claim 1, wherein the rotational axis of the rotary head is tilted to correspond to the recording speed of the recorded tape so that the scanning locus of the rotary head is parallel to the recording track. Replication device. 4. The videotape duplicating apparatus according to claim 1, wherein the rotating heads in the rotating cylinder that face each other at 180 degrees have different azimuth angles. 5. A videotape duplicating apparatus according to claim 1, wherein the rotating heads are arranged at the same angle with respect to the center of the rotating cylinder.